In a known design, such a starter contactor comprises a cylindrical annular armature, in which a solenoid coil or winding is arranged, the winding actuating a core which is movable axially within the armature so as to act on a control rod which extends axially through the centre of a fixed core. The fixed core is in the form of a disc and is arranged at a front axial end of the armature. The control rod effects axial displacements of a movable contact in and out of cooperating contact with two fixed power contact terminals that are connected, on the outside of the contactor, with the power supply circuit for the starter motor. These fixed contacts are mounted in the base of an end cap or cover which has the general form of a cylindrical pot, with a lateral skirt or side wall. The armature and the end cover thus together constitute a hollow casing of the contactor, the interior of which is an internal contactor chamber, and the movable contact is inside this chamber.
It is also known to control the contactor by means of an electronic control circuit which includes a support, typically consisting of a printed circuit board with electronic components carried by this support. In some known designs, the electronic control circuit is mounted inside a fully sealed housing which is then fixed on the outside of the starter, either on the support pedestal (or equivalent) of the starter, or on the contactor itself, or on the yoke of the electric starter motor. The housing for the electronic control circuit may also be fixed on the bodywork of the vehicle within the engine compartment.
It is then necessary in all cases to provide wires or cables which connect this housing, firstly with the starter contactor, and secondly with the other parts of the vehicle which are necessary for the control of starting of the engine, such as the ignition switch, the steering lock, an electronic computer unit for controlling fuel injection and ignition, and so on.
Thus the arrangement of the electronic control circuit within an independent housing makes it necessary to provide an additional component, which occupies space, which requires additional electrical connections, and which makes it necessary to carry out additional assembly operations on the vehicle.